Strings of sport rackets and method for making the same

ABSTRACT

A method for making strings for sport rackets includes a step of extruding two wires of different materials and a step of twining the two wires along an axis to form a string. The string includes a core wire of a first material and a sun-wire of a second material is twined to the core wire. No acid-wash is needed and the two steps can be completed within one machine.

FIELD OF THE INVENTION

The present invention relates to a method for making strings for sport rackets wherein no acid-wash is needed in the method, and the string includes at least two wires of different materials.

BACKGROUND OF THE INVENTION

The strings for sport rackets are required to absorb more energy when the ball hits the net of the sport racket and the stored energy transfers to the ball which then bounces back at high speed. Generally, the higher resilient factor the strings have, the better that the ball can be hit back. The conventional strings are made by Nylon, artificial fibers, catgut, or semi-catgut, wherein the artificial fibers are most welcomed for the strings.

The conventional string includes a plurality of wires which are twined with each other so as to form a string having high resilient feature and durable for being used for long time. As shown in FIG. 9, the conventional method for making the strings for sport rackets includes steps of extruding, acid-washing and twining. There are two different extruders for extruding “A” wire and “B” wire, both of the “A” wire and “B” wire are acid-washed to have rough surfaces, and the acid-washed “A” wire and “B” wire are twined at a pre-set arrangement. A material “C” is poured into the twining machine during twining the “A” wire and “B” wire so as to form a string.

However, there are too many machine involved for making the string, at least two extruders, one acid-washing machine and a twining machine are needed. In other words, the conventional strings are made at a high manufacturing cost, and the chemical acid material has environmental concerns.

The present invention intends to provide a method for making strings for sport rackets and only one machine is needed, and no acid-washing step is involved.

SUMMARY OF THE INVENTION

The present invention relates to a method for making strings for sport rackets and the method includes a step of extruding two wires of different materials and a step of twining the two wires along an axis to form a string.

The present invention relates to a string for sport rackets and the string includes a core wire of a first material and a sun-wire of a second material is twined to the core wire.

The primary object of the present invention is to provide a method that uses only one machine to make the string of sport rackets and no acid-wash step is needed.

The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the two steps of the method of the present invention;

FIG. 2 shows the arrangement of the machine for making the string of the present invention;

FIG. 3 is a cross sectional view to show the string of the present invention;

FIG. 4 is a cross sectional view to show another embodiment the string of the present invention;

FIG. 5 is a cross sectional view to show yet another embodiment of the string of the present invention;

FIG. 6 is a cross sectional view to show yet another embodiment of the string of the present invention;

FIG. 7 is a cross sectional view to show yet another embodiment of the string of the present invention;

FIG. 8 is a cross sectional view to show yet another embodiment the string of the present invention, and

FIG. 9 shows steps of a conventional method for making a string of sport rackets.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, the method for making strings of the present invention for sport rackets comprises the following steps:

a step of extruding: extruding two wires of different materials, and

a step of twining: twining the two wires along an axis to form a string.

Referring to FIGS. 2 and 3, the method is completed on one machine 10 which includes an extruder 20 and two tanks 21, 22 are connected to the extruder 20. Two different materials “A” and “B” are respectively received in the two tanks 21, 22 and fed into the extruder 20. The extruder 20 extrudes a core wire 51 by the material “A” and twelve sub-wires 52 by the second material “B”. Each of the core wire 51 and the sub-wires 52 has a circular cross section.

A third tank 23 is connected to a twining device 30 and a third material “C” is received in the third tank 23. The core wire 51 and the sub-wires 52 are twined to each other by the twining device 30 and the material “C” is added during twining so as to fill the space between the core wire 51 and the sub-wires 52 to form a string 50.

The string 50 can be made in the machine 10 and no acid-washing step is needed. Because the acid-washing step might damage the surface of the core wire 51 and the sub-wires 52 and causes loss of resilient feature, so that the method of the present invention ensures that the core wire 51 and the sub-wires 52 are reliable as they really are. The string 50 of the present invention can be made to have smaller diameter while all of the desired features are included so that the method can save a lot of material.

FIG. 4 shows that a plurality of core wires 51 are used and twined to be the string 50 and the material “C” is used to fill the gaps between the core wires 51 and to be coated on the outer surface of the string 50.

FIG. 5 shows a core wire 51 having a larger diameter and a plurality of sub-wires 52 with smaller diameter are twined to the core wire 51. The material “C” is used to fill the gaps between the core wires 51 and the sub-wires 52, and to be coated on the outer surface of the string 50.

FIGS. 6 to 8 disclose different types and shapes of the strings 50 by the three materials “A”, “B” and “C”.

While we have shown and described the embodiment in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention. 

1. A method for making strings for sport rackets, comprising: a step of extruding: extruding two wires of different materials; a step of twining: twining the two wires along an axis to form a string.
 2. The method as claimed in claim 1, wherein the two wires are extruded with pre-set shapes.
 3. The method as claimed in claim 1, wherein the two wires are extruded in a pre-set arrangement.
 4. The method as claimed in claim 1, wherein the two wires are twined as a string in a pre-set arrangement.
 5. A string for sport rackets, comprising: at least two wires which are made by first and second materials respectively, the at least two wires being twined and a third material mixed within the string.
 6. The string as claimed in claim 5, wherein the two wires are twined in a pre-set arrangement.
 7. The method as claimed in claim 5, wherein each of the two wires has a pre-set shape.
 8. The method as claimed in claim 1, wherein the string includes a core wire of the first material and sub-wires of the second material are twined to an outer periphery of the core wire, the third material is filled between the core wire and the sub-wires. 